"John Doe" wrote in message
...
Jeff Findley wrote:
That's the point of the COTS program. Still, if that falls through,
there
is Progress, ATV, and possibly HTV.
Does anybody really believe that private industry will develop some
automated cargo ship with all the guidance systems that would allow it
to get near enough the station to be berthed to a CBM hatch in just a
couple of years ?
The EU had Kurs to use as a template to develop their own system. NASA
has none of this that private contractors could use as a template.
Developping another ATV is pointless. It would still be limited by the
tiny russian hatches.
COTS isn't going to use Russian docking ports. COTS will be grabbed by the
SSRMS and berthed to a CBM, similar to the MPLM's.
Again, that's the point of the COTS program. Also, there is the
possibility
that if Ares/Orion continues that we would see Orion flights to ISS.
Well, if Orion flies, it may do a couple of weekend camping trips to the
moon, but its main purpose will be to act as a ferry to/from the
station. If it flies. But that still doesn't solve the issue of cargo.
Why not? It's concievable that you could launch an Orion unmanned and dock
or berth it to ISS. Apollo CSM's and LM's were flown umanned in LEO, so why
not Orion?
It's also concievable that you could launch an Orion minus its pressurized
reentry vehicle and use it to deliver unpressurized cargo to ISS. Note that
this is essentially how the Russians stripped down a Progress and used it to
launch Piers to ISS. If the Russians can do this, NASA can too.
ATV is pretty huge. It makes Progress look puny by comparison.
Same tiny russian hatches. Great for food/supplies, but can't bring
racks up/down.
So what? Entire racks are nice to bring up and down, but is NASA really
bringing down entire racks today with the shuttle and the MPLM's?
top of that, ISS was never designed to be an assembly location. You'd
almost certainly have lots of issues to deal with that would require
upgrades to ISS. For example, the CMG's might not have enough control
Upgrades to ISS wouldn't be needed. As you would grow the mars
expedition ship, the later's systems would take over or complement from
the station's system. When the ship leaves, then the station reverts to
its own systems.
That's a lot of hand waving going on there. In the long run, I think it
would still be cheaper to launch a new LEO assembly station than pay the
payload penalty on every assembly flight to get to ISS.
In terms of assembly capabilities, the station will have great
capabilities for that. The arm, the cupolla and exsiting human life
support and existing system to bring supplies.
All nice things to have, but I can't imagine the cost savings here would pay
for the ongoing payload penalty of launching to ISS.
If you start from scratch, you will end up with something similar to the
station where it will take a very long time before you can start to
really do a lot of work there. You'll get a few minimal modules (like
Zarya and Zvezda) and until you get large neough structure to support an
arm, electrical power etc, then you can't have people stay there for
long periods of time.
ISS certainly wasn't very big when the SSRMS was added. From NASA's website
www.nasa.gov, "Launched on STS-100 (assembly flight 6A) in April 2001, the
next generation Canadarm is a bigger, better, smarter version of the space
shuttle's robotic arm."
Here's a few pictures:
http://mix.msfc.nasa.gov/IMAGES/MEDIUM/0102190.jpg
http://www.ik1sld.org/iss_flt6a.htm
As you can see, the station at that point included two Russian modules, US
Node 1, the US Lab, and one US solar array module. At that point, I'd think
you'd have a pretty capable station for use as an assembly location.
Note also that the US pressurized modules were launched pretty empty and had
to be outfitted using MPLM flights due to the payload hit you take getting
to ISS's inclination. If the station were located at KSC's preferred
orbital inclination, this would have reduced the total number of US launches
needed.
With the station, you start off with all the necessary supplies (ECLSS,
Power, telecom) as well as hardware (airlock, arm) needed to do assembly
work.
You can replicate all of this with maybe six to eight shuttle/Proton sized
launches from the US if you choose a sane orbital inclination.
The question then becomes: how long would it take to assemble the ship
standalone until it has gained all the functions/services that the
station can provide.
And remember that a mars expedition ship will likely be a international
endeavour. Perhaps even the chinese would participate.
Maybe. Unfortunately, NASA is abandoning this approach with Ares/Orion and
trying to eliminate orbital assembly from the plan. The only assembly they
want in LEO is docking Orion to the huge stack of hardware launched by Ares
V. This will do nothing to prepare NASA for how to assemble hardware in LEO
for a Mars mission.
Jeff
--
A clever person solves a problem.
A wise person avoids it. -- Einstein